Connectors having various kinds of plastic housings (hereinafter, referred to simply as "connectors") have conventionally been used for connecting circuits of electric and electronic instruments or devices for use in motor vehicles. With the recent progress in the production of lower-pollution motor vehicles, there is a growing demand for more lightweight connectors. Further, with the trend toward performance and function increase in motor vehicles, the connectors have come to be required to, have a smaller size, more complicated form, improved heat resistance, improved fitting feeling, etc. The connectors are also required to have improved productivity.
Connectors made of a polybutylene terephthalate resin (hereinafter, sometimes referred to as "PBT resin") which have been used in motor vehicles in a large number are excellent in heat resistance, dimensional stability, moldability, and other properties. However, these connectors have had a problem of large weight due to the high specific gravity of the PBT resin.
Although 6-nylon resins and 6,6-nylon resins may be advantageously used for the weight reduction of connectors since these resins have lower specific gravities than PBT resins, the nylon resins have had a problem that they exhibit high moisture absorption, and therefore the connectors suffer a dimensional change and deterioration in mechanical property upon moisture absorption. Thus, 6-nylon and 6,6-nylon resins fail to satisfy the demand for size reduction, moldability to the complicated shape, and improvement in fitting feeling of connectors.
Other attempts have been made to reduce the weight of connectors by foaming or by incorporating a hollow filler, but such techniques have been defective in, for example, that accurate molding is difficult and the deterioration of mechanical properties is severe.
There has not been a connector which satisfies all the performance requirements.